A polymer formed article (e.g., plastic film) that is inexpensive and exhibits excellent workability has been provided with a desired function, and used in various fields.
For example, a gas barrier plastic film that does not allow water vapor and oxygen to pass through has been used as a food/drug packaging film in order to suppress oxidation and denaturation of proteins, oils, fats, and the like to keep taste and freshness.
In recent years, use of a transparent plastic film as an electrode substrate instead of a glass plate has been studied for displays (e.g., liquid crystal display and electroluminescence (EL) display) in order to implement a reduction in thickness, a reduction in weight, an improvement in flexibility, and the like. However, since a plastic film tends to allow water vapor, oxygen, and the like to pass through as compared with a glass plate, a deterioration in an element provided in a display may easily occur.
In order to solve the above problem, Patent Document 1 proposes a flexible display substrate in which a transparent gas barrier layer formed of a metal oxide is stacked on a transparent plastic film.
However, since the transparent gas barrier layer formed of a metal oxide is stacked on the surface of the transparent plastic film by evaporation (deposition), ion plating, sputtering, or the like, cracks may occur in the gas barrier layer when the substrate is rolled up or bent, so that the gas barrier capability may deteriorate.
Patent Document 2 discloses a method that produces a gas barrier film by forming a polysilazane film on at least one side of a film, and subjecting the polysilazane film to a plasma treatment. When using the method disclosed in Patent Document 2, however, a sufficient gas barrier capability cannot be obtained unless the thickness of the gas barrier layer is increased to a micrometer level. For example, Patent Document 2 states that a water vapor transmission rate of 0.50 g/m2/day was obtained when the gas barrier layer had a thickness of 0.1 μm.